We propose upgrading an existing A.E.I. MS-12 mass spectrometer using state-of-the-art electronics, a new higher field magnet and a data system. The resulting instrument will be fitted for fast atom bombardment (FAB) mass spectrometry and made available to a group of support research projects. The resulting data should greatly advance the probability of each research projects reaching their individual objectives. The availability of a FAB mass spectrometer in the Rocky Mountain Region will be advertised and a mechanism for new projects not included in this proposal is proposed. The biological studies to be supported by this instrument include: (1) The structure elucidation of complex glycolipopolysaccharides isolated from the pathogenic bacteria Mycobacterium leprae and M. kansasii. These antigenic determinants of the mycobacteria have molecular weights that range from 1500 to 3000 daltons and are available in quantities which should allow direct FAB mass spectrometry analysis. (2) Quantative analysis of steroid conjugates in urine, plasma and saliva using stable isotopes as reference compounds will be carried out. This approach could lead to a rapid method for steroid and drug level analysis and to a method that replaces purifying as it is done today. (3) A laboratory that has developed a proven capability to synthesize biologicall important compounds is engaged in a number of clinical research projects using these compounds. They need verification of the compounds that are generated during the laboratory synthesis. The FAB instrument would aid them to identify naturally occurring peptides that have been isolated and shown to have biological activity. (4) The amino acid sequence of tryptic peptides derived from phosphoproteins generated during mucin secretion in rat submandibular gland will be investigated by FAB. These studies should further our understanding of the regulation of protein phosphorylation in exocrine secretory systems and in disease states such as cystic fibrosis. (5) Several lines of evidence suggest that leukotrienes are metabolized by synthetic biotransformation pathways to higher molecular weight species. LTB4 may be incorporated into phospholipids as a mechanism for chemotaxis; LTC4 may be conjugated by glucuronyl transferases in the liver. FAB mass spectrometry is currently the only method to structurally analyze leukotriene C4/D4 and is well suited for phospholipid analysis.